Pattern controls for circular knitting machines

ABSTRACT

Pattern controls for circular knitting machines. The needle cylinder has in each of its grooves a lifting jack beneath which there is an upper tiltable selecting jack, and situated beneath the upper selecting jack is a lower selecting jack, this series of jacks in each groove being pivotally connected at their ends so that through tilting of the selecting jacks the lifting jack can be moved to or from an operating position. The upper tiltable selecting jack has a positive-selection butt to be engaged by a cam for swinging the lifting jack to its operating position, while the lower tiltable selecting jack has both a positive and a negative selection butt, both of which can be engaged by selecting cams for bringing about movement of the lifting jack either to its operating position or away from its operating position.

United States Patent [191 Comas 1 July 24, 1973 PATTERN CONTROLS FOR CIRCULAR KNITTING MACHINES [22] Filed: June 18, 1971 [21] Appl. No.1 154,402

[30] Foreign Application Priority Data Sept. 11, 1910 Spain 383923 [52] 1.1.8. Cl. 66/50 B [51] Int. Cl D04b 15/74 [58] Field oi Search 66/50 R, 50 B, 75, 66/25, 42, 36 A, 36 B [56] References Cited UNITED STATES PATENTS 3,004,413 10/1961 Felker 66/50 B 3,616,654 11/1971 Llinas 66/25 3,641,786 2/1972 Burdett et al.. 66/50 B 3,667,254 6/1972 Paepke 66/50 R FOREIGN PATENTS OR APPLICATIONS 996,291 6/1965 Great Britain 66/50 B 614,427 12/1960 Italy ..66/50R Primary Examiner-Wm. Carter Reynolds Attorney-Harold D. Steinberg et a1.

[57] ABSTRACT Pattern controls for circular knitting machines. The needle cylinder has in each of its grooves a lifting jack beneath which there is an upper tiltable selecting jack, and situated beneath the upper selecting jack is a lower selecting jack, this series of jacks in each groove being pivotally connected at their ends so that through tilting of the selecting jacks the lifting jack can be moved to or from an operating position. The upper tiltable selecting jack has a positive-selection butt to be engaged by a cam for swinging the lifting jack to its operating position, while the lower tiltable selecting jack has both a positive and a negative selection butt, both of which can be engaged by selecting cams for bringing about movement of the lifting jack either to its operating position or away from its operating position.

6 Claims, 6 Drawing Figures VIII/1110111717111;

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SHEET 3 OF 4 INVENTOR JOfiGT RECTOAET COM/13 Ma -4M ATTORNEYS PATTERN CONTROLS FOR CIRCULAR KNITTING MACHINES BACKGROUND OF THE INVENTION The present invention relates to circular knitting machines.

In particular, the present invention relates to pattern controls for circular knitting machines.

As is well known, circular knitting machines have in each groove of the needle cylinder thereof longitudinally movable lifting jacks which respectively coact with needles thereover for starting the upward movement of the needle so as to bring about the knitting op erations. These lifting jacks are swingable to and from operating positions where they coact with the cams of the knitting machine. Thus when the lifting jacks are in their inoperative positions the butts of the lifting jacks are situated beyond the cams so that the lifting jacks will not be raised and the needles thereover will not participate in the operations.

An upper selecting jack is usually pivotally connected with the lifting jack to determine whether or not it is in its operative or inoperative position depending upon the tilted position of the upper selecting jack. This latter jack is in turn pivotally connected to and located over a lower selecting jack which is tilted to act through the upper selecting jack for determining the position of the lifting jack. Positive selections are normally made by the upper selecting jacks, in the sense that when the latter are tilted by selecting cams the lifting jacks will be displaced to their operating positions, while negative selections are conventionally made by the lower selecting jacks in the sense that when these lower selecting jacks are tilted by suitable pattern earns the tilting movement is transmitted to the lifting jack for displacing the latter to its inoperative position.

Conventional pattern control structure of the above type has a number of drawbacks in that an exceedingly large number of differentjacks must be used for obtaining a given pattern, and a considerable amount of time and complex structure are involved in the adjustment of the selecting structures which determine the 'positions of the selecting jacks. As a result of all of these drawbacks the possibilities of economically operating a circular knitting machine to achieve a wide variety of complex patterns are greatly reduced.

SUMMARY OF THE INVENTION It is accordingly a primary object of the present invention to provide for circular knitting machines a pattern-controlling structure which will eliminate the above drawbacks.

In particular, it is an object of the present invention to provide a pattern mechanism which will enable the number of different jacks required for a given pattern to be substantially reduced.

Also it is an object of the present invention to provide a structure which will greatly facilitate the changing of a pattern.

In addition, it is an object of the present invention to provide a pattern-controlling structure which will have available two or more patterns, previously prepared, which can be very rapidly replaced without any substantial interruption in the operation of the machine.

According to the present invention the circular knitting machine has in each groove of its needle cylinder a lifting jack, for raising a needle thereover, and beneath this lifting jack an upper tiltable selecting jack, while beneath the latter there is a lower tiltable selecting jack. The upper selecting jack has an upper end pivotally connected to the lower end of the lifting jack and a lower end pivotally connected to the upper end of the lower selecting jack. Each upper selecting jack has a positive-selection butt to be engaged by a cam which swings the upper selecting jack to displace the lifting jack to its operating position. The lower selecting jack has a negative-selection butt to be engaged by a selecting cam which swings the lower selecting jack to provide a corresponding swinging of the upper selecting jack and movement of the lifting jack to its inoperative position. In addition each lower selecting jack has a positive-selection butt to be engaged by a cam for acting through the upper selecting jack on the lifting jack to displace the latter also to its operating position, so that positive selections for displacing the lifting jack to its operating position are made not only with the upper selecting jacks but also with the positive-selection butts of the lower selecting jacks.

BRIEF DESCRIPTION OF DRAWINGS The invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

FIG. 1 is a fragmentary sectional elevation, taken in a plane which contains the axis of the cylinders of the machine, and showing the arrangement of the jacks of the invention in a groove of the needle cylinder together with the pattern-selecting structure of the invention;

FIG. 2 is a sectional plan view taken along line 2-2 of FIG. 1 in the direction of the arrows and showing the negative-selection cams together with part of the structure for supporting a lower pattern drum;

FIG. 3 is a sectional plan view taken along line 3-3 of FIG. 1 in the direction of the arrows and showing lower positive-selection cams together with the stepping means for incrementally turning the lower pattern drum through a given angle at each revolution of the machine; I

FIG. 4 is a sectional plan view taken along line 4-4 of FIG. 1 in the direction of the arrows and showing the upper positive-selection cams together with the upper pattern drum and the lower pattern drum with the cap of the latter removed;

FIG. 5 is a sectional plan view taken along line 5-5 of FIG. 1 in the direction of the arrows and showing the structure over the upper pattern drum as wellas showing the lower pattern drum, with the outer cover of the pattern structure removed; and

FIG. 6 is a fragmentarysectional elevation, taken along line 6-6 of FIG. 2 in the direction of the arrows and showing the structure for actuating the stepping means which incrementally turns the lower pattern drum.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to FIG. 1, there is fragmentarily illustrated therein the lowerrotary rim or gear I which carries the needle cylinder having the lower portion 2 provided with grooves for the selecting jacks and the upper portion 3 provided with grooves for the lifting jacks and needles. This rotary member 1 is driven in a known way so that it will rotate the cylinder 2, 3. Bolts 4 and 5 are provided for respectively connecting the lower cylinder portion 2 to the rotary member I and the upper cylinder portion 3 to the lower cylinder portion 2, so that in this way a unitary rotary structure is provided.

The lower cylinder portion 2 is formed with axial grooves 6 which are respectively aligned with and forms continuations of the axial grooves 7 which are formed in the upper cylinder portion 3. The grooves 7 accommodate the needles and lifting jacks 8, and these lifting jacks are provided with butts 9 for coacting with cams of the stationary cam cylinder 38, these cams providing for the butts 9 and cam path 10. The particular lifting jack 8 which is shown in FIG. 1 only at its lower end region, is illustrated in FIG. 1 in its operating position where the butt 9 thereof is situated in the cam path 10 so that in this operating position of the lifting jack 8 it will be raised in order to raise a needle thereover and thus place this needle in operation. However, the lifting jack 8 can be displaced to the left, as viewed in FIG. 1, toward the common axis of the needle and cam cylinders, to an inoperative position where the butt 9 will be situated inwardly beyond the cam path 10, and thus in this inoperative position a needle located over the lifting jack will not participate in the operations.

Each groove 6 of the lower cylinder portion 2 accommodates in its interior an upper selecting jack 11 and a lower selecting jack 12. In an annular groove 15 of the cylinder portion 3 are a pair of tensioned circular springs 14 which engage in suitable notches formed in the upper selecting jacks 11 so as to urge them against the circular surface portion 13 of the cylinder portion 3. These selecting jacks II have tilting edges engaging the circular surface portion 13. As is apparent from FIG. 1, the tilting edge of each jack 11 has a crest situated at an elevation slightly higher than the springs 14, so that the latter tend to swing the jacks 11 to the position shown in FIG. 1.

The upper end of each selecting jack 11 is formed with an elongated cutout 16 for receiving the lower elongated end portion 17 of a lifting jack 8, so that in this way the lower end of the lifting jack 8 is pivotally connected to the upper end of the upper selecting jack 11. Thus, each upper selecting jack 11 can rock in a counterclockwise direction, as viewed in FIG. 1, about the crest of its tilting edge for displacing the butt 9 inwardly beyond the cam path 10 so as to maintain a lifting jack in its inoperative position.

Each upper selecting jack I1 initially has the butts 18, and these butts are removable so that each jack 11 will have one of these butts. Thus, as is well known, the first of a series of circumferentially arranged jacks ll of a given knitting unit, of which there are many in the relatively large circular knitting machine of the type shown in the drawing, will have only the lowermost butt 18, to coact only with the lowermost cam 19 illustrated in FIG. 1. The next of this series of jacks 11 will have only the second butt from the bottom, to coact with the second cam 19 from the bottom, the third jack 11 will have the third butt from the bottom, to coact with the third cam 19 from the bottom, and so on, so that in this way the butts of a series of jacks ll of a given knitting unit will be arranged along a helix respectively at the elevations of the several earns 19 which form positive selection cams in that when these cams are displaced to the left, as viewed in FIG. 1, toward the common axis of the needle and cam cylinders, their left operating ends will be situated in an engaging position in the path of movement of the positive-selection butts 18, so that if any of these butts are swung to the right, from the position shown in FIG. 1, they will engage a corresponding cam 19 and be displaced to the left, resulting in rocking of the selecting jack 11 to the position shown in FIG. 1 where it places the lifting jack 8 in its operating position. Thus, the upper series of cams 19 shown in FIG. 1 form a series of positive-selection cams for coacting with the positive-selection butts 18 of the upper tiltable selecting jacks 11 for swinging the latter to locate the lifting jacks thereover in their operating positions, in accordance with which of the cams 19 are displaced to their cam-engaging positions, as described below.

The several lower tiltable selecting jacks 12 are respectively arranged in the grooves 6 respectively beneath the upper selecting jacks 11. Each jack 12 also has a tilting edge directed toward the common axis of the cylinders, and this edge has a crest 20 about which the lower selecting jack l2 is'capable of tilting. The lower cylinder portion 2 is formed with an annular groove 22 supporting the elastic rings 21 which are tensioned and which coact with the lower jacks 12 to urge them to the positions shown for the jack 12 in FIG. 1. At its upper end each jack 12 is formed with a notch 23 receiving the lower end 24 of the upper selecting jack l1 thereover, so that in this way each pair of selecting jacks l1 and 12 in a groove 6 are pivotally connected to each other. Above the tilting crest 20 each jack 12 has a positive-selection butt 25 while below its crest 20 each lower selecting jack 12 has a negativeselection butt 26. Thus, it will be understood that the butts 25 shown in FIG. 1 are removable so that one of these butts will remain on a given jack 12 to coact with one of the selecting cams 27, and these butts 25 are also arranged along a helix as described above in connection with the butts 18, so that a given cam 27 can be radially shifted to a cam-engaging position for engaging a butt 25.

In the same way the butts 26 are removable to leave on each tiltable lower selecting jack 12 a negativeselection butt 26 which will coact with one of the negative-selection earns 28.

Because the cams 27, which form a lower series of positive-selection cams, and the positive-selection butts 25 of the lower selecting jacks 12 are situated above the crest 20 of each jack 12, these earns 27 and butts 25 are capable of extending the range of positive selections which can be made by way of the upper series of positive-selection cams l9 and butts 18. When a cam 27 engages a butt 25 the tilting jacks 11 and 12 will assume the position shown in FIG. 1 where a lifting jack 8 is also located in its operating position.

However, when one of the negative-selection cams 28 has been displaced in a manner described below to its engaging position for engaging a butt 26, the lower selecting jack 12 will be tilted in a clockwise direction, as viewed in FIG. 1, for displacing its upper end 23 radially away from the common axis of the cylinders, thus rocking the upper selecting jack 11 in a counterclockwise direction about its crest at the surface portion 13, just above the springs 14, with the result that the particular lifting jack 8 will be swung inwardly toward the common axis of the cylinders, displacing its butt 9 inwardly away from the cam path 10, so that in this way negative selections are made in the sense that the selected needles are maintained in positions where they do not participate in the knitting operations.

A support means is provided in order to support the various components which do not rotate with the needle cylinder, and this support means includes the circular base 29 which fixedly carries for each of the knitting units a housing structure 30 in the form of a suitable box in which is accommodated the rotary pattern drums and the structure of the support means which supports the several series of cams 19, 27, and 28 for horizontal radial movement, as described in greater detail below. It is to be understood that each knitting unit includes a cam for raising each needle to a yarn-taking position, after the needle has first been initially raised through a given increment by a lifting jack, and this particular cam is then followed'by the loop-sinking cam which serves to return the needle back down to its initial elevation. A large number of such knitting units are circumferentially distributed about the common axis of the cylinders.

The housing 30 of each knitting unit is divided by a horizontal partition into an upper compartment 31 and a lower compartment 32. The upper series of positiveselection cams 19 are located in the upper compartment 31, while the lower series of positive-selection cams 27 and the negative-selection cams 28 are both located in the lower compartment 32. As is apparent from FIGS. 2-4, toothed guide plates 33 are fixed by screws 34 to the housing 30 in such a way that the several cams 19, 27, and 28 are received between the teeth of these guide plates 33 so as to be supported for horizontal shifting movement.

The upper end of each housing 30 carries a block 35 and is threaded with a bolt 36 which serve to fix over the housings 30 the ring 37 which carries the cam cylinder 38 fixed to the ring 37 by way of the bolts 39.

Referring to FIGS. 1 and 5, the outer portion of each upper compartment 31 is formed with a pair of axially aligned orifices 40 and 41. The upper orifice or bore 40 receives a sleeve 42 which has a projecting fastening flange 43 through which extends a fixing screw 44. The sleeve 42 has a pair of tightening flanges 45 capable of being pulled together by a suitable screw, and these flanges 45 serve to fix in the sleeve 42 and bore 41 a spindle 46 of the upper pattern drum 48. The upper end of the spindle 46 fixedly carries a knob 47 accessible to the operator, for facilitating the handling of the spindle 46.

The tubular drum 48 is freelyturnable on the spindle 46. At its exterior the drum 48 is formed with a pair of diametrically opposed axially extending grooves 49 which respectively receive the camming plates 50, which are also visible in FIG, 4. Each camming plate 50 is formed along its outer edge with a series of cams 51, selected ones of which can be removed so as to provide a given pattern control from each camming plate 50. The spindle 46 passes through apertures of a pair of end plates 52 which are fixed to the drum 48 by way of screws 53. While only two grooves 49 and camming plates 50 are shown, it is of course to be understood that more than two grooves and camming plates 50 can be provided if desired.

The upper end plate 52 is formed with upper radial grooves 54 which are diametrically opposed and situated in angular alignment with the camming plates 50. These grooves 54 form part of a releasable holding means for releasably holding the upper pattern drum 48 in the angular position to which it is manually turned by the operator. For this purpose the releasable holding means includes a swingable catch member 55 supported for turning movement on a pin 56 extending across a suitable notch formed at the outer region of the upper wall of the housing 30, and thus, this catch member 55 can be turned to enter into one of the radial grooves 54 in order to angularly hold the drum 48 releasably in a selected angular position which will situate a selected one of the camming plates 50 in an operative position for engaging the outer ends of the several cams 19. Thus, the upper pattern drum 48 is manually turnable in order to situate a selected camming plate in an operative position with respect to the upper series of positive-selection earns 19.

The lower series of positive-selection cams 27 and the negative-selection cams 28 are controlled by a lower pattern drum assembly 57. This assembly includes a lower support plate 58 forming part of the support means. This base plate 58 is fixed to the top surface of the base 29 by way of screws 59, visible in FIG. 2, for example. The base plate 58 is formed with a bottom recess which receives a nut 61. This nut 61 is turnable on a lower threaded portion of an elongated spindle 62 which has a lower portion extending through an elongated slot 60, shown in FIGS. 1 and 2. The nut 61 is of a width greater than the slot 60, and the spindle 62 carries a flange or collar of a diameter greater than the width of the slot 60 situated directly over the latter on the base plate 58, so that the nut 61 can be loosened for adjusting the radial position of the lower pattern drum, and then the nut 61 can be tightened for fixing the lower pattern drum along the radially positioned slot 60.

The spindle 62 serves to support for rotary movement the lower pattern drum 63 held on the spindle 62 by a pair of lock nuts 64 with suitable spring washers 65 interposed between the lock nuts 64 and the drum 63.

An outer sleeve 67 is fixed to and surrounds the drum 63, this sleeve 67 being keyed to the drum 63 by way of a key 66. This sleeve 67 is formed with exterior axially extending grooves 68 distributed circumferentially about the axis of the spindle 62 and respectively receiving a series of camming plates 70 which are held in position by the elastic ring 69. The number of camming plates 70 is apparent from FIG. 4. Each camming plate 70 is formed with an upper series of camming projections 71 and a lower series of camming projections 72. These projections are situated at elevations for respectively cooperating with the upper series of the cams 27 and the lower series of cams 28. In this case also it is to be understood that at each plate 70 certain ones of these projections 71 will be removed so as to leave each plate 70 with a given upper camming projection 71 and a given lower camming projection 72 for coacting respectively with one of the upper earns 27 and one of the lower cams 28.

The rotary drum 63 carries a cap 74 which is threaded onto the upper end of the drum 63 in order to house the lock nuts 64. The lower edge of the cap 74 engages the upper ends of the camming plates 70 while pressing their lower ends against a washer 73. The upper end of the drum 63 is provided with the thread 75 for receiving the inner threads of the cap 74.

A stepping means is provided for stepping the lower pattern drum 63 at each revolution of the needle cylinder through an angular increment which will displace one of the camming plates 70 away from its operating position coacting with the cams 27 and 28 while displacing the next camming plate 70 into an operating position. This stepping means includes a ratchet wheel 77 fixed by screws 76 to the lower end of the drum 63. This ratchet wheel 77 is shown most clearly in FIG. 3. In addition to the ratchet wheel 77, the stepping means includes a pawl 78 pivoted at 79 on a swingable lever 80 supported for swinging movement on a pin 81. The lever 80 is swung about the pin 81 from the position shown in FIG. 3 in a counterclockwise direction to displace the pawl 78 from the solid line to the dotted line position shown in FIG. 3, in order to step the ratchet wheel 77 through an angular distance equal to that occupied by one tooth of the ratchet wheel, at each oscillation of the lever 80, and a pin 82 is resiliently urged against the pawl 78 by a spring 83 to urge the pawl 78 to return to the position shown in FIG. 3 with respect to the lever 80. The pin 82 and spring 83 are housed in a suitable bore in the lever 80.

At its left end, as viewed in FIG. 3, the lever 80 carries an adjustable stop screw 84 which has a free end to be engaged by the actuating projection 85 of a slide 86 shown in greater detail in FIG. 6. Thus, the base plate 58 is formed with an opening 87 through which the projection 85 extends to engage the element 84 carried by the lever 80. The slide 86 is pulled toward the axis of the cylinders by a spring 89 while being guided in an elongated groove 88 formed at the lower surface of the plate 58. This groove 88 extends radially with respect to the common axis of the cylinders.

The slide 86 has a lower projection 90 extending through a radial slot 91 formed in the base plate 29, and the rotary gear 1 carries an unillustrated cam which engages a cam follower roller 93 carried by a pin 92 which is threaded into the projection 90. Thus, at each revolution of the needle cylinder a cam carried by the rotary member 1 will engage the follower roller 93 so as to displace the slide 86 radially away from the axis of the cylinder, thus pushing the projection 85 into engagement with the stop 84 in order to swing the lever 80 and thus cause the pawl 78 to step the lower pattern drum to the next angular position where the next camming plate 70 will coact with the lower cams 27 and 28 in the lower compartment 32 of the housing 30.

The lower pattern drum 63 will therefore present another camming plate 70 to the several earns 27 and 28 so as to change the selection of needles at each revolution of the needle cylinder.

As is apparent. from FIGS. 2-4, conventional springs 94 are operatively connected with the several cams 19, 27, and 28 to urge them away from the common axis of the cylinders into retracted positions where they will not engage the butts of the selecting jacks. Thus, wherever a camming projection has been removed from a camming plate 70, the springs 94 will retract the corresponding cam to an inoperative position.

In order to change any pattern for which the machine has been set, it is a simple matter to remove the screws 96 and remove the cover 95 so as to give access to the pattern drums. Then it is a very simple matter to quickly remove the cap 74 so that the entire lower sleeve 67 with all of the camming plates 70 carried thereby can readily be slipped off the drum 63 and replaced by a previously prepared different sleeve 67 with different camming plates thereon. This operation can of course take place very rapidly even though the particular machine may have a large number of knitting units as referred to above.

In addition it is easily possible at any time, after removing only the screws 96 and the cover 95, to have immediate access to the catch 55 which can be raised out of a radial groove 54, thus releasing the upper pattern drum so that it can be turned to remove one of the camming plates 50 from cooperative relation with the cams l9 and replace it with the other camming plate 50. Then the catch 55 is replaced in its holding position. Thus, the controls previously provided by the left camming plate 50 of FIG. 1 can be changed by using the right camming plate 50 of FIG. 1, and this new set of controls can be achieved in an extremely simple and rapid manner.

It is thus apparent from the above description that it is possible with the structure of the invention to achieve the required combinations for a given pattern with a substantially smaller number of different jacks than has heretofore been possible since the number of jacks required for each group belonging to a given knitting unit is determined by the number of available jack butts. The number of possible combinations available for a given pattern will correspond to the product achieved by multiplying the numbers of stops of both of the selecting jacks, and thus it is clear that with the invention an extremely large number of patterns can be achieved with an exceedingly small number of jacks.

What is claimed is:

1. In a circular knitting machine, a needle cylinder formed with axial grooves and accommodating in each groove a lifting jack, beneath said lifting jack an upper tiltable selecting jack, and beneath said upper selecting jack a lower tiltable selecting jack,said upper selecting jack having an upper end pivoted to a lower end of said lifting jack and a lower end pivoted to an upper end of said lower selecting jack, said upper selecting jack having a butt for engaging a selecting cam which tilts said upper jackfor swinging said lifting jack to an operative position where it will be lifted, for placing a needle thereover in operation, said lower selecting jack having a negative-selection butt for engaging a selecting cam which-tilts said lower selecting jack to tilt said upper selecting jack for swinging said lifting jack to an inoperative position where it will not raise a needle, and said lower selecting jack also having a positive-selection butt for engaging a selecting cam to tilt said upper selecting jack for also swinging said lifting jack to its operative position.

2. The combination of claim 1 and wherein said lower selecting jack has a tilt edge provided with a crest situated at an elevation between the elevations of said positive and negative selection butts thereof.

3. The combination of claim 1 and wherein an upper series of positive-selection cams are situated at the elevation of the upper selecting jacks for coacting with the butts thereof, a lower series of positive-selection cams are situated at the elevation of the positive-selection butts of said lower selecting jacks for coaction with the latter butts, and a series of negative-selection cams are situated at the elevation of the negative-selection butts of said lower selecting jacks for coaction with the latter butts, support means supporting all of said cams for movement toward and away from said selecting jacks into and out of engaging positions for engaging the butts of said selecting jacks, upper pattern drum means situated at the elevation of said upper series of positiveselection cams for coacting therewith to displace selected cams thereof to their engaging positions, and lower pattern drum means situated'at the elevation of said lower series of positive-selection cams and said negative-selection cams for displacing selected lower positive-selection cams and negative-selection cams to their engaging positions.

4. The combination of claim 3 and wherein said upper pattern drum means has a predetermined axis of rotation and carries a plurality of elongated camming plates distributed about its axis of rotation, extending parallel thereto, and each provided with a plurality of camming projections for engaging selected ones of said upper series of positive-selection cams to displace the selected ones thereof to their engaging positions, so that depending upon the angular position of said upper pattern drum a given one of said plates thereof will determine the positions of the upper series of positiveselection cams, and said lower pattern drum means having a predetermined axis of rotation and carrying a plurality of elongated camming plates distributed about the latter axis of rotation and each having one series of camming projections for engaging selected ones of said lower series of positive-selection cams and a second series of camming projections for engaging selected ones of said negative-selection cams, so that depending upon the angular position of said lower pattern drum means selected ones of said lower series of positive-selection cams and selected ones of said negative-selection cams will be displaced to their engaging positions.

5. The combination of claim 4 and wherein said upper pattern drum means is manually turnable, and releasable holding means for releasably holding said upper pattern drum means in a selected angular position to which it is manually turned and stepping means coacting with said lower pattern drum means for stepping the latter through an angular increment displacing one camming plate away from a cam-engaging position and the next camming plate into a cam-engaging position automatically in response to rotary movement of said jacks and cams one with respect to the other about the axis of the needle cylinder.

6. The combination of claim 5 and wherein said upper pattern drum means has only two camming plates while said lower pattern drum means has a number of camming plates substantially greater than two. 

1. In a circular knitting machine, a needle cylinder formed with axial grooves and accommodating in each groove a lifting jack, beneath said lifting jack an upper tiltable selecting jack, and beneath said upper selecting jack a lower tiltable selecting jack,said upper selecting jack having an upper end pivoted to a lower end of said lifting jack and a lower end pivoted to an upper end of said lower selecting jack, said upper selecting jack having a butt for engaging a selecting cam which tilts said upper jack for swinging said lifting jack to an operative position where it will be lifted, for placing a needle thereover in operation, said lower selecting jack having a negative-selection butt for engaging a selecting cam which tilts said lower selecting jack to tilt said upper selecting jack for swinging said lifting jack to an inoperative position where it will not raise a needle, and said lower selectinG jack also having a positive-selection butt for engaging a selecting cam to tilt said upper selecting jack for also swinging said lifting jack to its operative position.
 2. The combination of claim 1 and wherein said lower selecting jack has a tilt edge provided with a crest situated at an elevation between the elevations of said positive and negative selection butts thereof.
 3. The combination of claim 1 and wherein an upper series of positive-selection cams are situated at the elevation of the upper selecting jacks for coacting with the butts thereof, a lower series of positive-selection cams are situated at the elevation of the positive-selection butts of said lower selecting jacks for coaction with the latter butts, and a series of negative-selection cams are situated at the elevation of the negative-selection butts of said lower selecting jacks for coaction with the latter butts, support means supporting all of said cams for movement toward and away from said selecting jacks into and out of engaging positions for engaging the butts of said selecting jacks, upper pattern drum means situated at the elevation of said upper series of positive-selection cams for coacting therewith to displace selected cams thereof to their engaging positions, and lower pattern drum means situated at the elevation of said lower series of positive-selection cams and said negative-selection cams for displacing selected lower positive-selection cams and negative-selection cams to their engaging positions.
 4. The combination of claim 3 and wherein said upper pattern drum means has a predetermined axis of rotation and carries a plurality of elongated camming plates distributed about its axis of rotation, extending parallel thereto, and each provided with a plurality of camming projections for engaging selected ones of said upper series of positive-selection cams to displace the selected ones thereof to their engaging positions, so that depending upon the angular position of said upper pattern drum a given one of said plates thereof will determine the positions of the upper series of positive-selection cams, and said lower pattern drum means having a predetermined axis of rotation and carrying a plurality of elongated camming plates distributed about the latter axis of rotation and each having one series of camming projections for engaging selected ones of said lower series of positive-selection cams and a second series of camming projections for engaging selected ones of said negative-selection cams, so that depending upon the angular position of said lower pattern drum means selected ones of said lower series of positive-selection cams and selected ones of said negative-selection cams will be displaced to their engaging positions.
 5. The combination of claim 4 and wherein said upper pattern drum means is manually turnable, and releasable holding means for releasably holding said upper pattern drum means in a selected angular position to which it is manually turned and stepping means coacting with said lower pattern drum means for stepping the latter through an angular increment displacing one camming plate away from a cam-engaging position and the next camming plate into a cam-engaging position automatically in response to rotary movement of said jacks and cams one with respect to the other about the axis of the needle cylinder.
 6. The combination of claim 5 and wherein said upper pattern drum means has only two camming plates while said lower pattern drum means has a number of camming plates substantially greater than two. 